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This page illustrates differences between tickets #104 and #105 for data creators using Scalar Coordinate Variables.

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In the examples, all variables are linked to a data variable, either as a coordinate variable or via the coordinates attribute, I have omitted this encoding to keep the table clearer.

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The right hand column shows a number of current uses of scalar coordinates we have encountered in software creating CF NetCDF datasets. All of these examples become invalid if #104 is implemented but remain valid if #105 is implemented.

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The left hand column indicates how we would have to change the current operations and output if #104 is accepted as a change to CF. In many cases decisions have to be made about which structure to encode which are currently not deemed necessary. In particular, these decisions are not currently made when the data set is written. The choice of appropriate structure is very case dependent.

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The proposed change #104 adds significant complexity to the data writing process, imposing decisions on data creators which they are not currently making as they are not deemed necessary in the cases illustrated below.

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In all these cases #104 is driving a change in my behaviour as a data creator, where as #105 is enabling me to carry on as I currently work, whilst clarifying the interpretation.

There are no examples of Discrete Sampling Geometries in this table, as #104 states: 'The interpretation of scalar coordinate variables in Section 9 may be different from the above, and this may require further clarification if the above is agreed'.

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In the absence of this clarification the only comment I can make about Scalar Coordinate Variables and Discrete Sampling Geometries is that #105 does not require further clarification, it is consistent with Section 9 of the Conventions document.